From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from wout3-smtp.messagingengine.com (wout3-smtp.messagingengine.com [64.147.123.19]) (using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id E358B3B29D for ; Wed, 26 Apr 2023 18:16:13 -0400 (EDT) Received: from compute3.internal (compute3.nyi.internal [10.202.2.43]) by mailout.west.internal (Postfix) with ESMTP id 435E83200920 for ; Wed, 26 Apr 2023 18:16:12 -0400 (EDT) Received: from imap44 ([10.202.2.94]) by compute3.internal (MEProxy); Wed, 26 Apr 2023 18:16:12 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=handley.org.uk; h=cc:content-type:content-type:date:date:from:from:in-reply-to :in-reply-to:message-id:mime-version:references:reply-to:sender :subject:subject:to:to; s=fm2; t=1682547371; x=1682633771; bh=Ix UcrS7EgCFJTLLFklsWZlVyjetGvH+uuNsGfWt6gEw=; b=e3bW0yHY5kbPXPYFJ5 eaEUUwSzwvGjHab/l9iCI8tRVNL5vL1E4X22XLFwjan3CrYD/YrsnpnWvnUZ2Orr VCCcrNyXtGrbuFoG/HD8bxvddG2czHpccilnfWezKAS/ksGGKAxuGSpqZHmuiS5g Nm17XI9WCFbrLAkGoRa5OIWCj2J9jX8uBZd7Jy26ods9T8iLcLEuhCs2qKtIBbwK QlmpNhZs2L7L8KpOpMktY/vHHAexcwpf0vVq3ZUpL0+cQ7m3A4X+YaV1yDF58j1y aiycmB/7XHvcrtgekUJJHbdJGXoTbxDsb8e72gipJ0A1FY7mVg1gO7JKGa9WrGxk eIiA== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:content-type:content-type:date:date :feedback-id:feedback-id:from:from:in-reply-to:in-reply-to :message-id:mime-version:references:reply-to:sender:subject :subject:to:to:x-me-proxy:x-me-proxy:x-me-sender:x-me-sender :x-sasl-enc; s=fm3; t=1682547371; x=1682633771; bh=IxUcrS7EgCFJT LLFklsWZlVyjetGvH+uuNsGfWt6gEw=; b=c5G6kLEeVTVCtKsv4YOekc2CBhV8W GMw88U4g3qgSy815D/sL6g9kAA9kin62nLRjEG1CYCPO3eCLtGtr2yrzauydWJ5L 8KF/uQa3iNYA2gI07eAtscy577IjnDJD5I37i7GbJ1tJ+DpyzoIaUfF5nTVa3Ajf 4avVWwRB+Ptuayk76rhVwW2zlpkUzBrilIKtlbNghW+H2lKHaP5g8YlahDhUpzNc zfmEl0lONZiQAyl6iulnweEA70bcOm8fFe2ctU3y5H/cqTpqamYm2xcOx8xHDeSH ExJJBapSmzqEx39Yn0W9mTOsmTUZkmmiCkTTB/beR74wQb2LsdRWr200A== X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedvhedrfeduhedgtdejucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucenucfjughrpefofgggkfgjfhffhffvufgtsegrtd erreerredtnecuhfhrohhmpedfofgrrhhkucfjrghnughlvgihfdcuoehmrghrkheshhgr nhgulhgvhidrohhrghdruhhkqeenucggtffrrghtthgvrhhnpeduleeuueefheeuuefgie dtieefgfegfeduieehfeefhfejkedvjeetjeegkeegtdenucffohhmrghinhepsghufhhf vghrsghlohgrthdrnhgvthenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepmh grihhlfhhrohhmpehmrghrkheshhgrnhgulhgvhidrohhrghdruhhk X-ME-Proxy: Feedback-ID: i4d08408c:Fastmail Received: by mailuser.nyi.internal (Postfix, from userid 501) id 9550A36A0073; Wed, 26 Apr 2023 18:16:11 -0400 (EDT) X-Mailer: MessagingEngine.com Webmail Interface User-Agent: Cyrus-JMAP/3.9.0-alpha0-374-g72c94f7a42-fm-20230417.001-g72c94f7a Mime-Version: 1.0 Message-Id: In-Reply-To: <1F70FD46-3CC0-47D5-9691-CE3FBA58F34A@ieee.org> References: <202304262041.33QKfOVh096953@gndrsh.dnsmgr.net> <1F70FD46-3CC0-47D5-9691-CE3FBA58F34A@ieee.org> Date: Wed, 26 Apr 2023 23:15:21 +0100 From: "Mark Handley" To: starlink@lists.bufferbloat.net Content-Type: multipart/alternative; boundary=819c782badb64f83bb8742e6e8350d54 Subject: Re: [Starlink] some post Starship launch thoughts X-BeenThere: starlink@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: "Starlink has bufferbloat. Bad." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 26 Apr 2023 22:16:14 -0000 --819c782badb64f83bb8742e6e8350d54 Content-Type: text/plain;charset=utf-8 Content-Transfer-Encoding: quoted-printable My understanding was that a pad water deluge system isn't primarily to r= emove energy from the exhaust plume itself, but rather to reduce the ext= reme sound level all the pad equipment and the booster are exposed to ou= tside of the exhaust plume. At really high sound levels you're achievin= g a near vacuum in the rarefactions of the sound waveform, and this low = pressure will cause water to boil, removing energy from the sound waves.= Or at least that's how I assumed it works :-) Mark On Wed, 26 Apr 2023, at 10:05 PM, Eugene Y Chang via Starlink wrote: > Rodney,=20 > I agree with your point of view. >=20 > To neutralize the exhaust of the rocket engine, it is all about taking= the energy out of the exhaust. Taking out the energy will slow the spee= d of the exhaust gas and take down the temperature.=20 >=20 > To get into more nitty gritty, the amount of heat absorbed by H2O or L= N2, depends on the dT (the temperature change) and also any heat of phas= e transition (e.g. liquid to gas). > Gene > ---------------------------------------------- > Eugene Chang > eugene.chang@ieee.org > o 781-799-0233 >=20 >=20 >=20 >> On Apr 26, 2023, at 10:41 AM, Rodney W. Grimes via Starlink wrote: >>=20 >>> As always I enjoy the flood of information we get on this list! >>>=20 >>> still, so far, my research on a nitrogen deluge system (instead of >>> water) has come up empty for me, except as a fire suppressant. So it= ?s >>> either crazy or brilliant. Or both! I really liked the idea of >>> something cooler that was a natural byproduct of the LOX process... >>=20 >> I dont think cooler does much, isnt it the "energy of vaporization" >> that is actually doing all the "work" in this type of system? >>=20 >> H2O is 40.7 kJ/mol and LN2 is 5.6 kJ/mol so you would >> need ~7 times as much LN2 to do the same work. >>=20 >> And the reason N2 is used as a fire suppressant is again not >> because of temperature, but because it displaces the O2 and >> suffocates the fire. N2 is also easier on our ozone layer >> than the prior used Halon. Finally, this is usually >> compressed N2 gas, not LN2. >>=20 >> -- >> Rod Grimes rgrimes@fr= eebsd.org >> _______________________________________________ >> Starlink mailing list >> Starlink@lists.bufferbloat.net >> https://lists.bufferbloat.net/listinfo/starlink > _______________________________________________ > Starlink mailing list > Starlink@lists.bufferbloat.net > https://lists.bufferbloat.net/listinfo/starlink >=20 >=20 > *Attachments:* > =E2=80=A2 signature.asc --819c782badb64f83bb8742e6e8350d54 Content-Type: text/html Content-Transfer-Encoding: quoted-printable
My understandin= g was that a pad water deluge system isn't primarily to remove energy fr= om the exhaust plume itself, but rather to reduce the extreme sound leve= l all the pad equipment and the booster are exposed to outside of the ex= haust plume.  At really high sound levels you're achieving a near v= acuum in the rarefactions of the sound waveform, and this low pressure w= ill cause water to boil, removing energy from the sound waves.  Or = at least that's how I assumed it works :-)

= Mark

On Wed, 26 Apr 2023, at 10:05 PM, Euge= ne Y Chang via Starlink wrote:
Rodney, 
I agree with your point of view.

To neutralize the exhaust of the rocket= engine, it is all about taking the energy out of the exhaust. Taking ou= t the energy will slow the speed of the exhaust gas and take down the te= mperature. 

To get into more nitty gritty, the amount of heat absorbed by H2O= or LN2, depends on the dT (the temperature change) and also any heat of= phase transition (e.g. liquid to gas).
Gene
-------------------------------------= ---------
Eugene Chang
o 781-799-0233



On Apr 26, 2023, at 10:41 AM= , Rodney W. Grimes via Starlink <starlink@lists.bufferbloat.net> wrote= :

As always I enjoy the flood of info= rmation we get on this list!

still, so far,= my research on a nitrogen deluge system (instead of
water= ) has come up empty for me, except as a fire suppressant. So it?s
either crazy or brilliant. Or both! I really liked the idea of
something cooler that was a natural byproduct of the LOX pr= ocess...

I dont think cooler d= oes much, isnt it the "energy of vaporization"
that is act= ually doing all the "work" in this type of system?

H2O is 40.7 kJ/mol and LN2 is 5.6 kJ/mol so you would
<= div>need ~7 times as much LN2 to do the same work.

And the reason N2 is used as a fire suppressant is again not
=
because of temperature, but because it displaces the O2 and
suffocates the fire.  N2 is also easier on our ozone l= ayer
than the prior used Halon.  Finally, this is usu= ally
compressed N2 gas, not LN2.

<= div>--
Rod Grimes       &nbs= p;           &nbs= p;           &nbs= p;           &nbs= p;     rgrimes@freebsd.org
_____________________= __________________________
Starlink mailing list
=
https://lists.bufferbloat.= net/listinfo/starlink
_______________________________________________
Starlink = mailing list


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